CMake: Port libadios2 to use the new FindMPI module

source/adios2/CMakeLists.txt

@@ -85,8 +85,7 @@ if(ADIOS2_HAVE_ZFP)
 endif()
 
 if(ADIOS2_HAVE_MPI)
-  target_include_directories(adios2 PUBLIC ${MPI_C_INCLUDE_PATH})
-  target_link_libraries(adios2 PUBLIC ${MPI_C_LIBRARIES})
+  target_link_libraries(adios2 PUBLIC MPI::MPI_C)
 else()
   target_sources(adios2 PRIVATE mpidummy.cpp)
 endif()